This invention relates generally to a type of device for detecting the existence of ice, that may cause an inadequate amount of friction, in the path of an automobile and alerting the driver to the existence of such roadway conditions.
A significant problem in driving during inclement weather conditions is that of ice on the roadway, with its obvious dangers to safe operation of a car or truck. Ice on the roadway can be visible if sunlight or artificial light is adequate, or it can be so-called black ice, which is extremely difficult for a driver to see until the vehicle is virtually on top of the icy patch, by which time it may be too late for the driver to safely slow the vehicle or control a turn with skidding. Additionally, the increasingly greater levels of sound insulation and ergonomic comfort features that are being provided in modern vehicles make it more likely that a driver will be in a less alert state of mind, and for that reason the driver may not detect the existence of ice on the road until it may be too late to correct the vehicle's speed or direction. Therefore, it has long been recognized that a need exists for some way of detecting the presence of ice in the path of a vehicle and of alerting the driver of such conditions before it is too late for the driver to compensate for such icy road conditions.
A significant problem is posed by the variety of roadway ice detectors that have been previously known in the art, in that they generally rely upon some type of optical sensor to detect the existence of precipitation on the roadway. Such sensors are generally disclosed to be somewhere under the vehicle carriage, which means that the sensors will be subjected to accumulation of roadway dirt, mud grime, and so forth, the accumulation of which on the sensor surface will assuredly degrade the accuracy and performance of the ice detection system. Therefore, a need exists in the art for a reliable accurate ice detection system that can sense, correct for and remedy the accumulation of roadway dirt on the critical sensor components of the system
It is therefore a goal of the present invention to provide for an optical roadway precipation sensing system that can detect for the presence of a dangerously great accumulation of roadway dirt on one or more components of the system. Another goal of the invention is to decrease the rate of accumulation of such dirt by shielding the componentry from such dirt as the vehicle travels along. Another goal of the invention is to be able to remove accumulations of such dirt from the componentry to maximize the performance of the system. Another goal of the invention is to incorporate into the ice warning system an ambient air temperature sensor that would take constant real time temperature readings of the air surrounding the vehicle and feed that data into the warning system. Yet another goal of the invention is to alert the driver when the ice warning system is not turned on by providing for an on/off switch that would be constantly illuminated when in the "Off" position, thus warning the driver that the system is not functional.
The invention features an electronic system to be installed on existing motor vehicles or incorporated into the production of new vehicles, which, when properly installed, can detect when road conditions are hazardous, especially with regard to being icy. The system features a dashboard-mounted display, a microprocessor unit, and a sensor unit which is mounted under the vehicle. The dashboard display is the driver's interface with the instrument. The sensor unit features a light source in either the visible or the infra-red range. The wavelength chosen is to maximize the difference in reflectance from a dry road surface to an icy surface. Since there is a possibility of light of a similar wavelength being introduced from an external source that could detract from the accuracy of the unit, the instrument's light beam is modulated, or turned on and off, at a specific rate to make it distinctive from outside illumination. The unit also features a second light source and receiver. The second light source and receiver are exposed to the same environment as the main sensor and include a reflective element to return a light signal to the receiver. Whenever dirt is present, this return signal is decreased. When a dirty sensor is detected, the dashboard display is disabled so that it will not give off a false signal, and additionally, distinctive lighting in the display will alert the driver to sensor innacuracy due to the presence of dirt on the unit. The invention features a microprocessor unit that handles the detection of signals returned from the road surface and whether the strength of the signal indicates ice or not. The microprocessor also monitors the dirt sensor signal to determine if dirt is impairing the accuracy of the unit. The sensitivity of the measurement signal changes in response to the amount of dirt present until there is so much dirt that accuracy could not be maintained. The invention further features calibration means to calibrate an individual unit to a particular installation. Other objects, features, and advantages of the invention will become more readily apparent to the reader from the following descriptions of the invention and its alternative embodiments.